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  #1  
Old 03-14-2008, 10:53 AM
ralph124c ralph124c is offline
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Can You "Shock" NiCd batteries back to Life?

I have several portable drills with dead batteries. Unfortunately, new batteries are not available 9not made anymore0, so i have to keep buying new drills. there is a guy on EBAY who claims that dead Nicd batteries can be shocked back to life-has anyone tried this? does it work?
And, WHY doesn't black& Decker KEEP the same damn battery design?
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  #2  
Old 03-14-2008, 11:12 AM
chrisk chrisk is offline
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Quote:
Originally Posted by ralph124c
And, WHY doesn't black& Decker KEEP the same damn battery design?
Apparently, to keep people buying new drills.

Sorry, don't have any info on the main question.
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Old 03-14-2008, 11:23 AM
beowulff beowulff is offline
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Applying a high-current pulse to a NiCd will sometimes burn off any "whiskers" that are shorting the plates. This will fix the battery for a while, but it will usually fail again in the near future.
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Old 03-14-2008, 11:28 AM
Spoons Spoons is offline
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I don't know about "shocking" a NiCad battery, but at a place I worked, we used to keep our NiCads working as long as possible through a process known as "conditioning" the battery. Basically, this was discharging the battery fully and recharging it again. We used a special battery conditioner for this, although I imagine you could also just run your equipment off the battery until it stops--this page concurs:

Quote:
Ni-Cad batteries remember how much charge was released on previous discharges. It has a tendency to release the same amount of energy with every charge/discharge cycle. If a Ni-Cad battery is always partially discharged before recharging, the usable capacity of the battery will be reduced.... A periodic discharge to one volt per cell or "exercise" is essential for Ni-Cad cells to prevent the building-up of memory. "Conditioning" (fully discharging and then fully charging) a battery pack also helps minimizing memory effect. Batteries can be fully discharged by disconnecting the equipment from the AC power supply and letting the equipment run on battery power until it ceases to function. Conditioning the battery once a month will keep it performing at its optimum level for a long time.
Sorry I cannot help more, and I don't know if you could condition your batteries back to life. But at least with this tip, you'll know how to maintain any NiCad batteries you get in the future.
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Old 03-14-2008, 02:49 PM
mwbrooks mwbrooks is offline
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Quote:
Originally Posted by beowulff
Applying a high-current pulse to a NiCd will sometimes burn off any "whiskers" that are shorting the plates. This will fix the battery for a while, but it will usually fail again in the near future.
To make this work (if it works at all), you should tear down the pack so you can test and condition the cells individually. As I understand it, it's possible (maybe even likely) that the bad cell is "reversed," so applying a pulse to the pack won't help the bad cell any.

Once you've torn the pack apart, you might as well take a cell to a battery store and see if you can buy a new set. The actual cells are probably one of the standard sizes that you can buy with solder tabs already welded on. Assembling a battery pack usually isn't all that hard, if you're fairly handy.

Before you do that, though, check your charger and make sure it's putting out the right voltage. The pack might not be bad at all if the charger's failed.

I should probably warn you to be careful in various ways. For example, don't replace NiCds with another type unless you know the charger can handle both. Don't replace just one cell in a pack, replace them all, with cells bought together. Be very careful not to short a cell or pack--NiCds don't explode as easily as some other types, but they can easily generate enough current to start a fire.

Good luck.
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  #6  
Old 03-14-2008, 04:10 PM
iamthewalrus(:3= iamthewalrus(:3= is offline
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Why not try it and see.

The worst that can happen is an explosion and maybe some serious chemical burns.
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  #7  
Old 03-14-2008, 05:16 PM
danceswithcats danceswithcats is offline
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A number of years ago I constructed a NiCd shocker using plans from Popular Science, hoping to extend the life of batteries used in pagers at my fire company.

Other than expending about $15 and an evening of my time, it didn't accomplish spit regarding battery life.
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  #8  
Old 03-15-2008, 12:39 PM
Rico Rico is offline
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Former two-way radio guy here.

Sometimes the problem is simply a "shorted cell." Charge the battery as much as you can, then check the voltage with a DVM. If it's supposed to be 12V and the DVM reads 9.6, you have two shorted cells (each cell is 1.2 volts). If this is the case, you can try the following:

WARNING: TAKE ALL PRECAUTIONS INCLUDING EYE PROTECTION WHEN TRYING THIS!

On a variable power supply, push voltage to 1.5 - 2 times the battery voltage.

Hook the power supply leads to a voltmeter. Preferably use an analog meter and slim probes. Set the voltmeter to read current.

Touch the negative lead to the negative charging terminal. Then, observing the analog meter, touch the positive lead to the positive charging terminal.

You will see the meter swing up, indicating current. When the shorted cells "pop" back in, you will see the meter drop, then immediately come back up, indicating current flow again. Stop at this point and charge the battery in the charger for at least 12 hours. This should give you a few more weeks of battery usage.

This overvoltage procedure should take no more than 3 seconds. If it hasn't happened in 3 seconds, STOP. Throw the battery away and buy a new one.

OTOH, if the battery reads full or no voltage after charging, don't bother trying this. Get a new battery. Ni-Cd batteries do wear out. The expected life is 1-2 years under normal use.

I take no responsibility for any misuse of this procedure. It's simply worked for me, many times, in the past.

Last edited by Rico; 03-15-2008 at 12:42 PM..
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